Folded sheets

ABSTRACT

The present invention relates to a sheet material which includes a first fold line and a second fold line. The first fold line and the second fold line are defined by a series of at least partial perforations in the sheet material. There are no at least partial perforations at an intersection of the first fold line and the second fold line. The sheet material is quadrilateral.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is filed as a divisional application under 35 U.S.C. §120 of U.S. patent application Ser. No. 10/380,521, filed on Aug. 25,2003.

FIELD OF THE INVENTION

The present invention relates to folded sheets, to methods of producingfolded sheets and to apparatus and methods for producing foldablesheets. The present invention further relates to related kits of parts.

BACKGROUND OF THE INVENTION

Various different ways of folding sheet material have been developed inorder to allow sheets containing relatively large amounts of informationto be reduced in size to manageable dimensions.

For example, European patent application number EP-A-0 288 472 disclosesa folded sheet comprising a first and second set of concertina folds,which sets are transverse to one another. The arrangement of foldsallows the sheet to be easily folded and unfolded by having stiffportions at diagonally opposite corner sections of the sheet.

Whilst folded sheets allow a large amount of information to be stored onan article of relatively small size, the method of manufacturing thefolded sheets is complicated. In order to provide the sheet with therequired folds complex folding apparatus is generally required.

The complex folding apparatus is a deterrent for small-scalemanufacturers and individuals wishing to produce such folded sheets.

It is an aim of preferred embodiments of the present invention toprovide a sheet material for producing folded sheets that overcomes atleast one of the disadvantages of the prior art folded sheets.

It is a further aim of preferred embodiments of the present invention toprovide apparatus and methods for producing foldable sheets.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda sheet material comprising a first fold line and a second fold line,the first and second fold lines being defined by a series of at leastpartial perforations in the sheet material, wherein there is one orfewer at least partial perforations at an intersection of the first foldline and the second fold line.

Generally, unless otherwise stated in this application or otherwiserequired by the context, the phrase “fold line” refers to a line alongwhich a fold can be formed and should not be taken to refer to a fold inthe sheet material. Although the fold lines are defined by at leastpartial perforations, they need not be pre-folded. Preferably, thefold-lines are not pre-folded.

A partial perforation can be an indentation in the sheet that does notpierce it. A full perforation fully pierces the sheet.

Preferably there is no at least partial perforation at an intersectionof a first fold line and a second fold line.

Suitably, there is a non-at least partly perforated section at anintersection of a first fold line and a second fold line.

Generally, unless otherwise stated in this application or otherwiserequired by the context, the phrase “non-at least partly perforatedsection” means a region in a series of at least partial perforations atwhich the spacing between the at least partial perforations is largerthan the spacing between at least partial perforations other than at thenon-at least partly perforated section. In the case of a series ofirregularly spaced at least partial perforations, a mean average ofspacing can be taken.

Suitably, the first and second fold lines are substantiallyperpendicular to one another.

The sheet material may comprise a plurality of first fold linesproviding a first set of fold lines. Suitably, the fold lines of thefirst set are substantially parallel to one another.

The sheet material may further comprise a plurality of second foldlines, providing a second set of fold lines. Suitably, the fold lines ofthe second set are substantially parallel to one another.

Suitably, there is one or less at least partial perforations at eachintersection of a first fold line and a second fold line. Preferably,there is a non-at least partly perforated section at each intersectionof a first fold line and a second fold line.

Suitably there is no overlap of at least partial perforations at anintersection of a first fold line and a second fold line. Suitably,there is no overlap of at least partial perforations at eachintersection of the first fold line and the second fold line.

According to a second aspect of the present invention, there is provideda sheet material comprising a first fold line and a second fold line,the first and second fold lines both being defined by a series of atleast partial perforations in the sheet material, wherein there is anon-at least partly perforated section at an intersection of a fold linewith an edge of the sheet material.

Suitably, the first and second fold lines are substantiallyperpendicular to one another.

The sheet material may comprise a plurality of first fold linesproviding a first set of fold lines. Suitably, the fold lines of thefirst set are substantially parallel to one another.

The sheet material may further comprise a plurality of second foldlines, providing a second set of fold lines. Suitably, the fold lines ofthe second set are substantially parallel to one another.

Suitably, a non-at least partly perforated section is provided at theintersection of each of the first set of fold lines and each of thesecond set of fold lines with an edge of the sheet material.

Suitably, the at least partial perforations stop short of anintersection of a fold line with an edge of the sheet material.Suitably, the at least partial perforations stop short of anintersection of each fold line with an edge of the sheet material.

Suitably, there is no overlap of an at least partial perforation with anedge of the sheet material.

According to a third aspect of the present invention there is provided asheet material comprising a first fold line and a second fold line, thefirst and second fold lines both being defined by a series of at leastpartial perforations in the sheet material, wherein there is one or lessat least partial perforation at an intersection of the first and secondfold lines and there is a non-at least partly perforated section at anintersection of a fold line with an edge of the sheet material.

Suitably, the first and second fold lines are substantiallyperpendicular to one another.

The sheet material may comprise a plurality of first fold linesproviding a first set of fold lines. Suitably, the fold lines of thefirst set are substantially parallel to one another.

The sheet material may further comprise a plurality of second foldlines, providing a second set of fold lines. Suitably, the fold lines ofthe second set are substantially parallel to one another.

Suitably, at each intersection of the first set of fold lines and thesecond set of fold lines there is one or less at least partialperforation.

Preferably there is no at least partial perforation, at the intersectionof the first fold line and the second fold line. Preferably there is noat least partial perforation at each intersection of the first fold lineand the second fold line.

Suitably, there is a non-at least partly perforated section at eachintersection of the first set of fold lines and the second set of foldlines.

Suitably, there is a non-at least partly perforated section at theintersection of each of the first set of fold lines and each of thesecond set of fold lines with an edge of the sheet material.

Suitably there is no overlap of at least partial perforations at anintersection of a first fold line and a second fold line. Suitably,there is no overlap of at least partial perforations at eachintersection of the first fold line and the second fold line.

Suitably, the at least partial perforations stop short of anintersection of a fold line with an edge of the sheet material.Suitably, the at least partial perforations stop short of anintersection of each fold line with an edge of the sheet material.

Suitably, there is no overlap of a at least partial perforation with anedge of the sheet material.

In each aspect of the present invention the series of at least partialperforations, when full perforations defining a fold line comprises aplurality of incisions in the sheet material, each incision providing afull perforation, which incisions are spaced apart from one another. Theincisions may be in the form of elongate lines or they may be in theform of dots.

Suitably, the spacing of the at least partial perforations in a non-atleast partly perforated section is substantially larger than the spacingbetween at least partial perforations other than at the non-at leastpartly perforated section.

Suitably, the spacing between at least partial perforations at thenon-at least partly perforated section is at least twice, preferably atleast three times and more preferably at least four times the length ofthe spacing between at least partial perforations other than at thenon-at least partly perforated section.

Suitably, the spacing between at least partial perforations at thenon-at least partly perforated section is less than twenty times,preferably less than fifteen times and more preferably less than tentimes the length of the spacing between at least partial perforationsother than at the non-at least partly perforated section.

The non-at least partly perforated section at an intersection of a firstand second fold line is suitably between 3-6 mm long, and preferablybetween 4-5 mm long, most preferably it is about 4 mm long.

Suitably, the non-at least partly perforated section at the intersectionof a fold line with an edge of the sheet is about 1-4 mm, preferably itis about 2 mm.

In each aspect of the invention, the spacing between a pair of adjacentat least partial perforations on a fold line may be greater than thelength of a at least partial perforation. For a series of non-uniformlength at least partial perforations, a mean average of the adjacent atleast partial perforations may be taken. However, the spacing betweenthe at least partial perforations may be the same as or less than thelength of the adjacent at least partial perforations.

The length of the at least partial perforations and the spacing betweenthe at least partial perforations will affect the ease with which a foldline can be folded, the strength of the fold line (or resistance totearing) and the ease with which the sheet will pass through a desk topprinter.

Generally, the larger the at least partial perforations length, theeasier it is to fold along a fold line. However, longer at least partialperforations are more susceptible to tearing during printing andhandling and sheets comprising fold lines defined by longer at leastpartial perforations are generally more difficult to feed through astandard desk top printer.

Shorter at least partial perforations are generally less susceptible totearing and sheets comprising shorter at least partial perforationsgenerally feed more easily through a standard desk top printer. However,fold lines defined by shorter at least partial perforations willgenerally be more difficult to fold.

These characteristics of the at least partly perforated sheet are notdefined solely by the at least partial perforation length. The spacingof the at least partial perforations will also be a relevant factor.

Suitably, the at least partial perforation length is no more than fivetimes, preferably no more than four times and more preferably no morethan three times the length of the spacing between adjacent at leastpartial perforations. Suitably, the at least partial perforation lengthis at least a quarter of, preferably at least half and more preferablyat least the same as the length of the spacing between adjacent at leastpartial perforations.

Generally, the shorter the spacing between adjacent at least partialperforations, the weaker the fold line will be and the easier the foldline will be to fold. Generally, the longer the spacing between adjacentat least partial perforations the stronger the fold line, but the moredifficult the fold line will be to fold.

The strength, foldability and printability of a sheet comprising foldlines defined by at least partial perforations will also be affected byother factors, such as, paper density and type (e.g. grain of paper).

The length of at least partial perforation and the spacing betweenadjacent at least partial perforations chosen will depend to a largeextent on the intended use of the final product. For some applicationseasier printing and stronger fold line will be more important than easeof folding.

In each aspect of the invention, the spacing between adjacent at leastpartial perforations is suitably uniform along the length of each foldline.

Alternatively, the spacing between adjacent at least partialperforations may vary along the length of each fold line.

Suitably, the spacing between adjacent at least partial perforations isthe same for all of the fold lines in the sheet material. Alternatively,the spacing between adjacent at least partial perforations may varybetween each fold line.

Suitably, the spacing between each at least partial perforation is atleast 0.5 mm, preferably at least 1 mm and more preferably at least 1.5mm. Suitably, the spacing between each at least partial perforation isless than 5 mm, preferably less than 4 mm and more preferably less than3 mm.

In each aspect of the invention, each series of at least partialperforations defining a fold line suitably comprises at least partialperforations of uniform length.

Alternatively, a series of at least partial perforations defining a foldline may comprise at least partial perforations of various differentlengths. In this case, the spacing between two adjacent at least partialperforations may be greater than the length of either of the two atleast partial perforations.

Suitably the length of each at least partial perforation is the same forall of the fold lines in a sheet material. Alternatively, the length ofthe at least partial perforations may vary between different fold lines.

Suitably, the length or diameter of each at least partial perforation isat least 0.25 mm, preferably at least 0.5 mm, more preferably at least 1mm and particularly at least 2 mm. Suitably, the length or diameter ofeach at least partial perforation is less than 5 mm, preferably lessthan 4 mm and more preferably less than 3 mm.

The at least partial perforations are intended to provide a means ofdefining the fold lines only. The at least partial perforations are notintended to provide tear lines in the sheet material. An advantage ofthe present invention is that at least partly perforated sheets forfolding are provided which have improved resistance to tearing along thefold line.

A sheet in accordance with any aspect of the invention may be providedwith at least one additional at least partly perforated line, which atleast one additional at least partly perforated line is or are designedto tear more easily than the at least partly perforated fold lines.Thus, a folded sheet may be provided with tear off sections.

One or more additional non-at least partly perforated sections may beprovided on a fold line as well as the non-at least partly perforatedsections at the intersections of first and second fold lines and theintersection of a fold line with the edge of a sheet.

Suitably, the additional non-at least partly perforated sections arelocated at regions of the fold line between intersections of fold linesand/or between a point of intersection of two fold lines and anintersection of a fold line with an edge of the sheet.

Provision of additional non-at least partly perforated sections alongthe length of a fold line advantageously improves the strength of a foldline.

The sheet material may comprise any substrate, but will usually be onethat takes print. Suitably, the sheet material comprises a paper basedsheet material. Any type and/or density of paper which can be used witha standard desk top printer can be used. For example, a suitable densityfor a paper sheet material is about 50-400 gsm. Alternatively, plasticsbased sheet materials or board may be used. If thicker sheet material isused, full perforations make folding easier.

The sheet size may be any suitable sheet size. Suitably, the sheet sizeis A3, A4, A5, foolscap or American legal.

By way of example, the sheet material may comprise a first set of foldscomprising a plurality of fold lines and a single second fold line.Suitably, the fold lines of the first set are substantially parallel toone another. Suitably, the second fold line is substantiallyperpendicular to the first set of fold lines.

In use of this embodiment of the invention, the first set of fold linesare first folded in a concertina fashion relative to one another todefine the folds, then the sheet is flattened out and the sheet isfolded along the second fold line, to define that fold. To assemble thesheet into a folded article, the sheet is suitably first folded aboutthe concertina fold lines and then the concertina folded sheet is foldedagain along the second fold line.

By way of example, the sheet material may comprise a first set of foldlines, comprising a plurality of fold lines that are substantiallyparallel to one another, and a second set of fold lines, comprising aplurality of fold lines that are also substantially parallel to oneanother. Suitably, the first set of fold lines is substantiallyperpendicular to the second set of fold lines.

In use of this embodiment of the invention, each of the first set offold lines is folded in a concertina fashion relative to one another.Preferably, the sheet is then unfolded and laid substantially flatbefore folding each of the second set of fold lines in a concertinafashion relative to one another. Flattening the sheet between foldingthe first and second sets of folds advantageously allows for better folddefinition of the second set of folds. To assemble the sheet into afolded article, the sheet is suitably concertina folded about the firstset of folds and then the concertina folded sheet is concertina foldedabout the second set of folds.

Any suitable arrangement of fold lines and manner of folding may beused. For example, a set of parallel fold lines need not be concertinafolded.

There are different types of at least partial perforations. Some atleast partial perforations provide only indentations in a sheet, whereasothers actually penetrate through a sheet. Again, the type of at leastpartial perforation chosen will depend to a large extent on the intendedapplication of the final product. Generally, at least partialperforations which do not penetrate the sheet provide stronger foldsthat are less susceptible to tearing, but are more difficult to fold.

Both types of at least partial perforations affect the nature of thesurfaces of the sheet. The top surface, onto which the at least partialperforations are applied, will generally be relatively smooth comparedto the bottom surface, because the at least partial perforations pushthe bottom paper surface outwards.

When folding a sheet along a at least partly perforated fold line it isgenerally easier to make the fold on the smooth surface (i.e. so thattwo sections of the smooth surface are bought into a face to facerelationship when the sheet is folded).

The sheet may be provided with visual indicia to indicate where and/orhow the sheet should be folded. The visual indicia may comprise printedinstructions on the sheet, for example. Alternatively, or in addition,the sheet material may be provided with watermarks therein to illustratea suitable manner of folding of the sheet.

When printing the sheet, information may be printed into discrete panelsprovided by intersection of first and second fold lines. Alternatively,or in addition, information may be printed over more than one panels ofthe sheet. Substantially the whole surface may be printed over. In thesecases, printing over a fold line may serve to enhance visibility of thefold line.

Any type of information for example, written or pictorial informationmay be printed onto the sheet. Furthermore, one or both surfaces of thesheet may receive printed information. The whole of each surface mayreceive print. Alternatively, or in addition, only part of a surface mayreceive print.

A sheet in accordance with any aspect of the present invention mayadvantageously be supplied with at least one cover portion. Suitably,the at least one cover portion is or are applied to the sheet after thesheet material has been printed. Suitably, the at least one coverportion is or are applied to the sheet after the sheet material has beenfolded.

Suitable cover portions include individual portions having a size aboutthe same as or, preferably, slightly larger than the size of a segmentof the sheet material once folded.

Alternatively, the at least one cover portion may comprise a portiondesigned to be folded over the sheet material when folded, in a similarmanner to the way a book cover folds around the pages of a book. Afold-over cover portion may comprise a plurality of fold lines toprovide a spine at the fold, allowing for improved coverage when usedwith thicker folded sheets.

The at least one cover portion suitably comprises a material that isthicker than the sheet material. Suitably, the cover portion is thinenough to feed through a standard desk top printer. The at least onecover portion may comprise a paper-based material, such as a boardmaterial. If a thicker board is required, sections may be removedtherefrom to provide holes in the cover portion.

The at least one cover portion may comprise a plastics material. Theplastics material may be opaque, translucent or transparent.Advantageously, the plastics material can be thicker than a board coverportion if it is translucent or transparent as it need not be fedthrough a printer.

The at least one cover portion may be attached to the sheet material byany suitable means. Suitably, the at least one cover portion is or areattached to the folded sheet material by means of an adhesive. Suitably,the adhesive is applied to the at least one cover portion in the form ofa pressure sensitive strip of adhesive. Suitably, the adhesive isprotected by a silicone release paper.

The adhesive may be applied to the cover portion and/or a region of thesheet. If the adhesive is applied to the sheet, it is suitably appliedto the region of attachment of the cover portion only.

In use, the sheet is suitably folded along the at least partlyperforated fold lines, then the silicone strip is removed from theadhesive strip and the at least one cover portion is applied to thefolded sheet material.

Suitably, the sheet material has a cover portion applied to oppositecorners of the sheet. The corners may be diagonally and/orlongitudinally opposite corners.

Information and/or decoration may be applied to a cover portion beforeor after it is applied to the sheet material. Suitably, informationand/or decoration is printed onto a cover portion. Suitably, informationand/or decoration is applied to a cover portion before it is applied toa sheet material.

If the at least one cover portion comprises a translucent or transparentplastics material, the information which would have been applied to thecover portion may be applied to the segment of the sheet material towhich the cover portion will be attached. In this case, there need notbe any information and/or decoration applied to the cover portion.Furthermore, a translucent or transparent cover portion allows use to bemade of the full surface of the sheet material.

Instead of or as well as a cover portion a segment of the sheet materialmay be treated to make it stiffer than the rest of the sheet. Forexample, a UV curable resin may be soaked, printed, or otherwise appliedto a segment and then cured to provide a stiff portion.

According to a fourth aspect of the invention, there is provided amethod of producing a folded sheet comprising the steps of:

-   -   (a) providing a sheet material according to any preceding aspect        of the present invention,    -   (b) applying information and/or decoration onto the sheet of        step (a), followed by    -   (c) folding the sheet material along fold lines defined by the        at least partial perforations.

Suitably, the information and/or decoration is printed onto the sheet.

The method may further include the step of applying one or more coverportions to the sheet material. The one or more cover portions may beapplied either before or after the sheet material is folded. Preferably,the one or more cover portions is or are applied to the sheet materialafter step (b).

The one or more cover portions may have information and/or decorationapplied thereto before the one or more cover portions is applied to thesheet. The cover portion suitably has information and/or decorationprinted thereon.

The method may involve use of folding and/or binding machinery.

According to a fifth aspect of the invention, there is provided a kit ofparts comprising a sheet material according to any other aspect of thepresent invention and a cover portion for attachment to the sheetmaterial.

The present invention advantageously provides a sheet material that canbe easily printed on, with a laser printer or the like, and then easilymanually folded to provide a folded printed sheet without therequirement for expensive folding machinery.

A folded sheet in accordance with preferred embodiments of the presentinvention advantageously allows an individual or small-scale printer toeasily produce printed folded sheets.

Furthermore, ensuring that there is a non-at least partly perforatedsection at the intersection of fold lines reduces the likelihood of atear developing at these intersections. Likewise, ensuring that there isa non-at least partly perforated section at the intersection of a foldline with an edge of the sheet reduces the likelihood of the sheettearing at the edge thereof at the fold lines.

Conventional at least partly perforated tear lines in sheet material canform ridges in the sheet. When a plurality of sheets are stacked one ontop of the other, these ridges can cause unevenness in the thickness ofthe stack. Furthermore, these ridges often can cause the sheet materialbeing fed through a printer to get stuck in the printer. Providing asheet having fold lines defined by at least partial perforations,wherein the spacing between the at least partial perforations is greaterthan the length of the at least partial perforations reduced the degreeof distortion of the sheet material in the region of the at leastpartial perforations and overcomes these problems associated with atleast partly perforated tear lines, thus allowing a stack of sheets tobe loaded on a printer and used without jamming the printer.Alternatively, the at least partial perforations may be misaligned.

Different patterns of at least partial perforations and non-at leastpartly perforated regions can be used to provide sheets having foldlines of different strengths. For example, greater spacing between theat least partial perforations and/or a greater number of non-at leastpartly perforated sections on a fold line will provide a stronger sheet,which is less susceptible to tearing.

For applications that are intended to be used for short periods, forexample, 1 day or 1 week, the fold lines need not be as strong as sheetsthat are intended to be used for much longer, say a year.

According to the present invention in a sixth aspect, there is providedapparatus for producing a foldable sheet, the apparatus comprising aplurality of rigid portions in a spaced array and means forsubstantially securing the rigid portions relative to one another.

The gaps between the rigid portions can be used to impress fold linesinto a sheet material by pressing the sheet into the apparatus, by handor, for instance, using a roller.

Suitably, the rigid portions are flexibly joined together so that asheet material can be laid on to the apparatus, which is folded asdesired, forcing the appropriate folded shape into the sheet material.

Suitably, the rigid portions are substantially rectangular. Suitably,the rigid portions are a sheet material (i.e. relatively thin).

Suitably, the rigid portions are metallic, preferably aluminium.

Suitably, the securing means comprises flexible plastic sheet to whichthe rigid portions are secured, preferably adhesively secured.

Suitably, the rigid portions are arranged in a substantially rectangulararray. Suitably, there are more rigid portions in one direction of thearray than the other.

Suitably, the apparatus is for producing a concertina foldable sheet.Suitably, the apparatus is for producing a sheet with a first set ofconcertina folds in a first direction and a second set of concertinafolds in a second direction, the first direction being generallytransverse to the second direction.

Suitably, the apparatus includes means for creating at least partialperforations in the fold lines of the sheet.

According to the present invention in a seventh aspect, there isprovided a method of producing foldable sheets, which method comprisesthe steps of: with an apparatus according to the sixth aspect of thepresent invention, forming fold lines in a sheet of material.

Suitably, the fold lines are formed by pressing the apparatus and thesheet together. This may be by one being forced into the other or thetwo being pressed together.

Suitably, the apparatus is folded about the sheet material.

According to the present invention in an eighth aspect, there isprovided apparatus for producing a folded sheet, the apparatuscomprising a roller, which roller comprises means for at least partlyperforating a sheet.

Suitably, the at least partial perforating means comprises a pluralityof spikes or a plurality of indentations.

According to the present invention in a ninth aspect, there is provideda sheet of material which has folds in it, regardless of whether it isin a folded up condition or not unless the context otherwise requires,and that takes folds at which it can be easily unfolded (without thefolds disappearing) and refolded, the sheet having a first set ofconcertina folds and, so as to be transverse to these when the sheet isfolded with these folds, a second set of concertina folds, in which thesheet is provide with two diagonally opposite, defined, stiff portionsat segments thereof, which segments are at or near diagonally oppositecorners of the sheet and defined by fold/s and/or edge/s thereof, whichsheet is according to any of the first to third aspects of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only,with reference to the following drawings, in which:

FIG. 1 is a schematic plan view of a sheet material;

FIG. 2 shows the sheet of FIG. 1 in a partially folded condition;

FIG. 3 shows the sheet of FIGS. 1 and 2 in a further folded condition;

FIG. 4 is a schematic plan view of an alternative sheet material;

FIG. 5 shows the sheet of FIG. 4 in a partially folded condition;

FIG. 6 shows the sheet of FIGS. 4 and 5 in a further folded condition,and

FIG. 7 shows a schematic plan view of another sheet material.

FIG. 8 shows a plan view of an apparatus for producing folded sheets.

FIG. 9 shows a schematic perspective view of a roller for use inproducing perforated sheets.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1, 2 and 3 show a sheet 2 comprising a first set of fold lineseach defined by a series of perforations 4 and a second fold linedefined by a series of perforations 8. The sheet 2 has opposed edges 10,12 and 14, 16 respectively.

The series of perforations 4, defining the first set of fold lines,comprise perforations of equal length being equally spaced from oneanother except at the non-perforated sections. The spacing between theperforations is greater than the length of the perforations.

The perforations 8, defining the second fold line, comprise perforationsof equal length being equally spaced apart from one another except atthe non-perforated sections. The spacing between the perforations isgreater than the length of the perforations.

The length of the perforations for each of the first set of fold linesand each of the second set of fold lines is 1.5 mm and the spacingbetween adjacent fold lines is about 0.75 mm.

Each series of perforations 4, 8 stop short of the relevant edges 10,12, 14 and 16 of the sheet material 2, providing a non-perforatedsection about 2 mm long.

Furthermore, there is a non-perforated section on each fold line at eachintersection 18 of a series of perforations 4, with the series ofperforations 8. Each of these non-perforated sections is about 4 mmlong.

The fold lines define a set of panels on the sheet comprising 6 columnsand two rows.

The sheet material 2 may be fed through a printer in either a landscapeor portrait orientation to impart information thereto.

Thereafter, the sheet 2 may be folded along the fold lines defined bythe series of perforations 4 and 8 to provide a more conveniently sizedproduct suitable for storage in a pocket. After folding the cover 28 isapplied to the sheet 2.

FIG. 2 illustrates a first stage of folding the sheet 2, wherein thesheet 2 is folded in a concertina fashion about fold lines 22, definedby series of perforations 4.

FIG. 3 illustrates a further stage of folding, wherein the folded sheetof FIG. 2 is folded along fold line 26, defined by series ofperforations 8.

FIG. 3 also illustrates how a fold over cover 28 may be located relativeto the folded sheet 2. The fold over cover 28 is illustrated by brokenlines. The cover 28 comprises a single piece of cardboard material, orthe like, which is folded about fold line 32 and then attached to theouter sections of the folded sheet 2. Suitably, the cover 28 is attachedto the folded sheet 2 by means of pressure sensitive adhesive strip (notshown).

To open the folded sheet 2, section 34 of the cover 28 is moved in thedirection indicated by arrow A, thereby unfolding the cover 28 aboutfold line 32 and unfolding the sheet 2 about fold line 26.

FIGS. 4, 5 and 6 illustrate an alternative sheet 50, comprising a firstset of fold lines, defined by series of perforations 52 and 54, and asecond set of fold lines, defined by series of perforations 56, 57, 58,59 and 60.

Each series of perforations 52, 54, 56, 58 and 60 comprisesnon-perforated regions 96 to provide stronger fold lines more resistantto tearing. The non-perforated regions 96 are between fold lineintersections and/or between a fold line intersection and anintersection of a fold line with an edge of the sheet.

The non-perforated regions 96 are about 2 mm long.

Each series of perforations 52, 54, 56, 57, 58, 59 and 60 all compriseperforations of equal length being equally spaced from one anotherexcept in the non-perforated sections. In each case, the spacing betweenthe perforations is greater than the length of the perforations.

In this embodiment the perforations are about 0.5 mm long and thespacing between adjacent perforations is about 0.5 mm.

Each series of perforations 52, 54, 56, 57, 58, 59 and 60 stops short ofthe edges 62, 64, 66 and 68 of the sheet 50, providing a non-perforatedsection in these regions about 2 mm in length.

Furthermore, at the points of intersection 70, 71, 72, 73, 74, 76, 77,78, 79 and 80 of the series of perforations 52 and 54 with the series ofperforations 56, 57, 58, 59 and 60 there is a non-perforated sectionabout 4 mm in length.

FIG. 5 illustrates a first stage of folding sheet 50, wherein the sheet50 is folded in a concertina along fold lines 81, 82, 83, 84 and 85defined respectively by series of perforations 56, 57, 58, 59 and 60.

FIG. 6 illustrates a further stage of folding the folded sheet 50 asshown in FIG. 5, wherein the sheet 50 is folded in a concertina fashionalong fold lines 86 and 88 defined respectively by series ofperforations 52 and 54.

FIG. 6 also shows, in broken lines, location of separate cover portions92 and 94 to the folded sheet 50, which cover portions 92, 94 areapplied to the sheet 50 by means of an adhesive (not shown). When foldedthe sheet 50 of FIGS. 4, 5 and 6 can conveniently be stored in a wallet.

FIG. 7 illustrates an A4 sheet 100 having a first set of fold linesdefined by perforated lines 102 and a second set of fold lines definedby perforated lines 104. The first and second sets of folds divide thesheet 100 into a series of panels 106. The panels 106 are arranged asthree columns and six rows.

The length of each perforation is about 1.5 mm and the spacing betweenadjacent perforations is about 1 mm. The non-perforated region 108 atthe intersection of first and second fold lines is about 4 mm and thenon-perforated region 110 at the intersection of a fold line with theedge of the sheet 100 is about 2 mm.

Suitably, the short edge of each panel 106 comprises about 17perforations and the long edge of each panel 106 comprises about 30perforations.

Alternatively, the perforations may be about 1 mm and the spacingbetween adjacent perforations may be about 0.5 mm. In this case, theshort edge of each panel 106 will comprise about 32 perforations and thelong side of each panel 106 will comprise about 47 perforations.

For an A4 sheet divided into three columns and six rows each short edgeof a panel 106 suitably comprises from 15-35 perforations and each longedge suitably comprises between 25-50 perforations.

Perforations may be full incisions or partial indentations.

FIG. 8 shows a jig or apparatus 200 for producing foldable sheets. Theapparatus 200 comprises an array of thin (about 1 mm) rectangularmetallic (aluminium or plastics) rigid portions 202. The rigid portions202 are in a rectangular array with more rigid portions in one directionthan the other (i.e. 6×2 in this example). The rigid portions 202 haveslight gaps 204 therebetween and are secured relative to one another byan adhesive plastics backing sheet 206.

In use a paper sheet to be folded is forced to take up fold lines fromthe apparatus 200 by either being pressed hard into the surface of theapparatus 200, using something along the lines of a rolling pin or,alternatively, the sheet to be folded is lain over the apparatus 200 andthe apparatus 200 is folded in the manner desired inducing fold lines inthe sheet. To emphasise the fold lines, a mating rigid plate (not shown)with protrusions aligning with gaps 204 can be used to sandwich thesheet in which fold lines are desired.

In an alternative embodiment, the rigid portions 202 may include spikesor projections to generate perforations in the fold lines of a sheet.

Indentations or full perforations can also be produced in a sheet usinga paper guillotine device that does not fully cut a sheet. Theguillotine blade may indent the sheet or include spikes or the like togenerate full perforations.

Referring to FIG. 9 of the drawings that follow, there is shown a roller210 usable to produce perforations in a sheet. The roller 210 hasoutwardly extending spikes 212 to generate perforations in a sheet asthe sheet passes the roller 210. A pinch roller (not shown) can be usedto press a sheet onto the spikes 212. Protrusions, instead of spikes,can be used to generate indentations. Preferably, the roller 210 ismounted in a printer (not shown) so the sheet can be printed and atleast partly perforated in one step.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings), may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention is not restricted to the details of the foregoingembodiment(s). The invention extend to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

1. A sheet material comprising a first fold line and a second fold line,the first fold line and the second fold line being defined by a seriesof at least partial perforations in the sheet material, wherein thereare no at least partial perforations at an intersection of the firstfold line and the second fold line, and wherein the sheet material isquadrilateral.
 2. A sheet material according to claim 1, in which thefirst fold line and the second fold line are substantially perpendicularto one another.
 3. A sheet material as claimed in claim 1, in which thesheet material comprises a plurality of first fold lines, providing afirst set of fold lines.
 4. A sheet material according to claim 3, inwhich the sheet material further comprises a plurality of second foldlines, providing a second set of fold lines.
 5. A sheet material asclaimed in claim 1, where there are no at least partial perforations ateach intersection of the first set of fold lines and second set of foldlines.
 6. A sheet material as claimed in claim 1, wherein there is anon-perforated section at an intersection of a fold line with an edge ofthe sheet material.
 7. A sheet material as claimed in claim 1, whereinthere are no at least partial perforations at the intersection of thefirst fold line and second fold line, wherein an intersection spacing isdefined, and wherein the intersection in a direction along either thefirst fold line or the second fold line is larger than the space inbetween the at least partial perforations of the first fold line or thesecond fold line.
 8. A sheet material comprising a plurality of firstfold lines providing a first set of fold lines, and transverse to thefirst set of fold lines a plurality of second fold lines providing asecond set of fold lines, the first set of fold lines and the second setof fold lines defining a plurality of segments, the first set of foldlines and the second set of fold lines being defined by a series of atleast partial perforations in the sheet material, where there are no atleast partial perforations at the intersections of the first set of foldlines and the second sets of fold lines, and wherein the first set offold lines and the second sets of fold lines define a plurality ofsegments of substantially the same dimensions.
 9. A sheet materialaccording to claim 8, in which the first fold lines and the second foldlines are substantially perpendicular to one another.
 10. A sheetmaterial according to claim 8, in which the fold lines of the first setare substantially parallel to one another.
 11. A sheet materialaccording to claim 8, in which the fold lines of the second set aresubstantially parallel to one another.
 12. A sheet material according toclaim 8, in which there are no at least partial perforations at eachintersection of a first fold line and a second fold line.
 13. A sheetmaterial as claimed in claim 8, wherein there is a non-perforatedsection at an intersection of a fold line with an edge of the sheetmaterial.
 14. A sheet material as claimed in claim 8, wherein there areno at least partial perforations at the intersection of the first set offold lines and the second set of fold lines, wherein an intersectionspacing is defined, and wherein the intersection in a direction alongeither the first set of fold lines or the second set of fold lines islarger that the space in between the at least partial perforations ofthe first set of fold lines or the second set of fold lines.